Collision mitigation of reference signals and a direct current subcarrier in wireless communication systems

ABSTRACT

The present disclosure relates to mitigating collision between reference signals and direct current subcarriers both occupying at least a same resource element of a resource block. Specifically, a UE may at least adjust a DMRS pattern within the resource block based on determining an upcoming occurrence of the collision between the DMRS and the DC subcarrier. Further, a network entity may determine that the UE should transmit the DMRS according to an adjusted DMRS pattern and transmit the adjusted DMRS pattern to the UE on a downlink communication channel.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of U.S. Provisional Application Ser.No. 62/505,452, entitled “COLLISION MITIGATION OF REFERENCE SIGNALS ANDA DIRECT CURRENT SUBCARRIER IN WIRELESS COMMUNICATION SYSTEMS” and filedon May 12, 2017, which is expressly incorporated by reference herein inits entirety.

BACKGROUND

Aspects of the present disclosure relate generally to wirelesscommunication networks, and more particularly, to collision mitigationof reference signals and direct current tones in wireless communicationssystems such as new radio.

Wireless communication networks are widely deployed to provide varioustypes of communication content such as voice, video, packet data,messaging, broadcast, and so on. These systems may be multiple-accesssystems capable of supporting communication with multiple users bysharing the available system resources (e.g., time, frequency, andpower). Examples of such multiple-access systems include code-divisionmultiple access (CDMA) systems, time-division multiple access (TDMA)systems, frequency-division multiple access (FDMA) systems, orthogonalfrequency-division multiple access (OFDMA) systems, and single-carrierfrequency division multiple access (SC-FDMA) systems.

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. For example, a fifth generation (5G)wireless communications technology (which can be referred to as newradio (NR)) is envisaged to expand and support diverse usage scenariosand applications with respect to current mobile network generations. Inan aspect, 5G communications technology can include: enhanced mobilebroadband addressing human-centric use cases for access to multimediacontent, services and data; ultra-low latency (ULL) and/orultra-reliable-low latency communications (URLLC) with certainspecifications for latency and reliability; and massive machine typecommunications, which can allow a very large number of connected devicesand transmission of a relatively low volume of non-delay-sensitiveinformation. As the demand for mobile broadband access continues toincrease, however, further improvements in NR communications technologyand beyond may be desired.

For example, for NR communications technology and beyond, collisionsbetween reference signals and direct current (DC) subcarriers on theuplink may inhibit a desired level of speed or customization forefficient operation. Thus, improvements in wireless communicationoperations may be desired.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

In an aspect, the present disclosure includes a method for wirelesscommunications at a user equipment (UE). The method may includedetermining an upcoming occurrence of a collision between a demodulationreference signal (DMRS) and a direct current (DC) subcarrier, theoccurrence of the collision being that both the DMRS and the DCsubcarrier occupy at least a same resource element within a resourceblock in a scheduled uplink transmission. The method may further includeadjusting a DMRS pattern within at least the resource block based ondetermining the upcoming occurrence of the collision.

In another aspect, the present disclosure includes an apparatus forwireless communications. The apparatus may include means for determiningan upcoming occurrence of a collision between a DMRS and a DCsubcarrier, the occurrence of the collision being that both the DMRS andthe DC subcarrier occupy at least a same resource element within aresource block in a scheduled uplink transmission. The apparatus mayfurther include means for adjusting a DMRS pattern within at least theresource block based on determining the upcoming occurrence of thecollision.

In an additional aspect, the present disclosure includes acomputer-readable medium storing computer executable code for wirelesscommunications. The computer-readable medium may include code fordetermining an upcoming occurrence of a collision between a DMRS and aDC subcarrier, the occurrence of the collision being that both the DMRSand the DC subcarrier occupy at least a same resource element within aresource block in a scheduled uplink transmission. The computer-readablemedium may further include code for adjusting a DMRS pattern within atleast the resource block based on determining the upcoming occurrence ofthe collision.

In yet another aspect, the present disclosure includes an apparatus forwireless communications comprising a memory and a processor coupled tothe memory. The processor may be configured to determine an upcomingoccurrence of a collision between a DMRS and a DC subcarrier, theoccurrence of the collision being that both the DMRS and the DCsubcarrier occupy at least a same resource element within a resourceblock in a scheduled uplink transmission. The processor may be furtherconfigured to adjust a DMRS pattern within at least the resource blockbased on determining the upcoming occurrence of the collision.

In an aspect, the present disclosure includes a method for wirelesscommunications at a network entity. The method may include determiningan upcoming occurrence of a collision between a DMRS and a DCsubcarrier, the occurrence of the collision being that both the DMRS andthe DC subcarrier occupy at least a same resource element within aresource block in a scheduled uplink transmission from a UE. The methodmay further include determining that the UE should transmit the DMRSaccording to an adjusted DMRS pattern. Moreover, the method may includetransmitting the adjusted DMRS pattern to the UE on a downlinkcommunication channel.

In another aspect, the present disclosure includes an apparatus forwireless communications. The apparatus may include means for determiningan upcoming occurrence of a collision between a DMRS and a DCsubcarrier, the occurrence of the collision being that both the DMRS andthe DC subcarrier occupy at least a same resource element within aresource block in a scheduled uplink transmission from a UE. Theapparatus may further include means for determining that the UE shouldtransmit the DMRS according to an adjusted DMRS pattern. Moreover, theapparatus may include means for transmitting the adjusted DMRS patternto the UE on a downlink communication channel.

In an additional aspect, the present disclosure includes acomputer-readable medium storing computer executable code for wirelesscommunications. The computer-readable medium may include code fordetermining an upcoming occurrence of a collision between a DMRS and aDC subcarrier, the occurrence of the collision being that both the DMRSand the DC subcarrier occupy at least a same resource element within aresource block in a scheduled uplink transmission from a UE. Thecomputer-readable medium may further include code for determining thatthe UE should transmit the DMRS according to an adjusted DMRS pattern.Moreover, the computer-readable medium may include code for transmittingthe adjusted DMRS pattern to the UE on a downlink communication channel.

In yet another aspect, the present disclosure includes an apparatus forwireless communications comprising a memory and a processor coupled tothe memory. The processor may be configured to determine an upcomingoccurrence of a collision between a DMRS and a DC subcarrier, theoccurrence of the collision being that both the DMRS and the DCsubcarrier occupy at least a same resource element within a resourceblock in a scheduled uplink transmission from a UE. The processor mayfurther be configured to determine that the UE should transmit the DMRSaccording to an adjusted DMRS pattern. Moreover, the apparatus may beconfigured to transmit the adjusted DMRS pattern to the UE on a downlinkcommunication channel.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed aspects will hereinafter be described in conjunction withthe appended drawings, provided to illustrate and not to limit thedisclosed aspects, wherein like designations denote like elements, andin which:

FIG. 1 is a schematic diagram of an example wireless communicationnetwork including at least one base station having a collision detectioncomponent and at least one user equipment (UE) having a collisionmitigation component;

FIGS. 2A-2D are conceptual diagrams of transmissions for one or moreresource block according to various DMRS patterns;

FIG. 3 is a flow diagram of an example of a method of wirelesscommunication at a UE;

FIG. 4 is a flow diagram of an example of a method of wirelesscommunication at a network entity;

FIG. 5 is a schematic diagram of example components of the UE of FIG. 1;and

FIG. 6 is a schematic diagram of example components of the base stationof FIG. 1.

DETAILED DESCRIPTION

Various aspects are now described with reference to the drawings. In thefollowing description, for purposes of explanation, numerous specificdetails are set forth in order to provide a thorough understanding ofone or more aspects. It may be evident, however, that such aspect(s) maybe practiced without these specific details. Additionally, the term“component” as used herein may be one of the parts that make up asystem, may be hardware, firmware, and/or software stored on acomputer-readable medium, and may be divided into other components.

The present disclosure generally relates to mitigating collisions, or atleast the effect of collisions between reference signals such as ademodulation reference signal (DMRS) and a direct current (DC)subcarrier. For example, during uplink transmission, a user equipment(UE) may transmit a DMRS within a slot for channel estimation. However,the DMRS may be scheduled on resources also occupied by a DC subcarrier,which may be used to locate a center of an OFDM frequency band (e.g., atleast one of the OFDM symbols may be the DC subcarrier). Further, one ormore resource elements on which the DC subcarrier is transmitted may beof lower error vector magnitude (EVM), which may be a measurementquantifying a performance of a radio transmitter/receiver. Theseresource elements may correspondingly be of lower quality, and so muchso that the UE may have difficulty in transmitting the DC subcarrier. Assuch, when the DMRS is scheduled on a resource element occupied by theDC subcarrier, a collision may occur and result in unreliable or corruptchannel estimation for that DMRS. Further, in instances where a lowresource block grant is provided by the network, such a loss of DMRStransmissions may adversely affect channel estimation at the UE,resulting in potentially poor uplink transmissions. Thus, it may bedesirable for the UE to adjust a DMRS pattern such that collision withthe DC subcarrier is mitigated, or in some instances, avoided entirely.

Accordingly, the present aspects may mitigate collisions between DMRSand a DC subcarrier. For example, in some aspects, a UE may determine anupcoming occurrence of a collision between a DMRS and a DC subcarrierboth occupying at least a same resource element within a resource blockin a scheduled uplink transmission. Further, the UE may adjust a DMRSpattern within at least the resource block based on determining theupcoming occurrence of the collision between the DMRS and the DCsubcarrier both occupying the at least a same resource element of theresource block in the scheduled uplink transmission. Additionally, insome aspects, a network entity (e.g., eNB) may determine an upcomingoccurrence of a collision between a DMRS and a DC subcarrier bothoccupying at least a same resource element within a resource block in ascheduled uplink transmission from a UE. The network entity may furtherdetermine that the UE should transmit the DMRS according to an adjustedDMRS pattern. Moreover, the network entity may transmit the adjustedDMRS pattern to the UE on a downlink communication channel.

Additional features of the present aspects are described in more detailbelow with respect to FIGS. 1-5.

It should be noted that the techniques described herein may be used forvarious wireless communication networks such as CDMA, TDMA, FDMA, OFDMA,SC-FDMA, and other systems. The terms “system” and “network” are oftenused interchangeably. A CDMA system may implement a radio technologysuch as CDMA2000, Universal Terrestrial Radio Access (UTRA), etc.CDMA2000 covers IS-2000, IS-95, and IS-856 standards. IS-2000 Releases 0and A are commonly referred to as CDMA2000 1x, 1X, etc. IS-856 (TIA-856)is commonly referred to as CDMA2000 1xEV-DO, High Rate Packet Data(HRPD), etc. UTRA includes Wideband CDMA (WCDMA) and other variants ofCDMA. A TDMA system may implement a radio technology such as GlobalSystem for Mobile Communications (GSM). An OFDMA system may implement aradio technology such as Ultra Mobile Broadband (UMB), Evolved UTRA(E-UTRA), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20,Flash-OFDM™, etc. UTRA and E-UTRA are part of Universal MobileTelecommunication System (UMTS). 3GPP Long Term Evolution (LTE) andLTE-Advanced (LTE-A) are new releases of UMTS that use E-UTRA. UTRA,E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from anorganization named “3rd Generation Partnership Project” (3GPP). CDMA2000and UMB are described in documents from an organization named “3rdGeneration Partnership Project 2” (3GPP2). The techniques describedherein may be used for the systems and radio technologies mentionedabove as well as other systems and radio technologies, includingcellular (e.g., LTE) communications over a shared radio frequencyspectrum band. The description below, however, describes an LTE/LTE-Asystem for purposes of example, and LTE terminology is used in much ofthe description below, although the techniques are applicable beyondLTE/LTE-A applications (e.g., to 5G networks or other next generationcommunication systems).

The following description provides examples, and is not limiting of thescope, applicability, or examples set forth in the claims. Changes maybe made in the function and arrangement of elements discussed withoutdeparting from the scope of the disclosure. Various examples may omit,substitute, or add various procedures or components as appropriate. Forinstance, the methods described may be performed in an order differentfrom that described, and various steps may be added, omitted, orcombined. Also, features described with respect to some examples may becombined in other examples.

Referring to FIG. 1, in accordance with various aspects of the presentdisclosure, an example wireless communication network 100 may include atleast one UE 110 with a modem 140 having a collision mitigationcomponent 170 that may adjust, via a DMRS pattern determinationcomponent 172, a DMRS pattern 176 based on determining that a collisionmay occur between a DMRS 178 and a DC subcarrier 162. Further, wirelesscommunication network 100 may include at least one base station 105 witha modem 160 including an collision detection component 150 that maydetermine an uplink transmission limiting scenario via the uplinklimitation determination component 174 based on one or more channelconditions and transmit an indication to the UE 110 denoting the uplinktransmission limiting scenario.

For example, with respect to the DC subcarrier 162 at the UE 110 (e.g.,the transmitter), the UE 110 may assume that the transmit DC subcarrier162 at the transmitter side (e.g., gNB) may be modulated such that datais neither rate-matched nor punctured. Further, the signal qualityrequirements (e.g., EVM) corresponding to DC subcarriers may be set bythe network. The forgoing may be performed with respect to downlinktransmissions. However, for the uplink, transmit DC subcarrier 162 atthe transmitter side (e.g., UE 110) may be modulated such that data isneither rate-matched nor punctured. Moreover, signal qualityrequirements (e.g., EVM) corresponding to DC subcarriers may be set bythe network. The DC subcarrier 162 at the UE 110 should avoid collisionswith at least the DMRS 178 transmissions for accurate channel estimationand efficient uplink transmissions. In some aspects, a particularsubcarrier may be defined as a candidate position of the DC subcarrier162, e.g., DC subcarrier is located at the boundary of physical resourceblocks (PRBs). Also, the receiver (e.g., gNB) may determine the DCsubcarrier 162 location, which may involve semi-static signaling fromthe UE 110 and/or a defined DC subcarrier 162 location within a resourceblock (e.g., a defined frequency band). In some aspects, the DCsubcarrier 162 may correspond to a DC subcarrier candidate. As such, inthe event of a collision between the DC subcarrier 162 and DMRS 178, asdetermined by the collision detection component 150 and/or the collisionmitigation component 170, the DMRS pattern 176 may be adjusted toaccount for the collision with the DC subcarrier 162.

Specifically, in some aspects, the UE 110 may adjust the DMRS pattern176 according to various schemes based on an initial DMRS pattern, oneor more channel conditions, or semi-static signaling from the basestation 105. The UE 110 may initially determine that an upcoming orexpected scheduled transmission of the DMRS transmission 178 and the DCsubcarrier 162 may result in a collision. In some aspects, a collisionmay occur when the DMRS 178 occupies or is transmitted on at least oneresource that is also occupied by or used for the DC subcarrier 178.That is, the DMRS 178 and the DC subcarrier are overlapping the sameresource elements forming the slot within the resource block.

For instance, upon a determination of an upcoming or expected collisionbetween a scheduled DMRS 178 transmission and a DC subcarrier 162, theDMRS pattern determination component 172 may determine a DMRS pattern176 that either or reduces the detrimental effect of the collision, oravoids the collision entirely. In one example, if the collision of theDMRS 178 with the DC subcarrier 162 cannot be avoided (e.g., and boththe UE 110 and the base station 105 are aware of the upcomingcollision), then the DMRS pattern 176 for the UE 110 may be adjusted viathe DMRS pattern determination component 172. Specifically, the DMRSpattern 176 may be changed to one that may handle the collision with theDC subcarrier 162 more effectively, thereby reducing the negativeeffects on channel estimation and uplink transmission, as furtherdescribed herein with respect to FIGS. 2A and 2B. In another example,the DMRS pattern determination component 172 may adjust the DMRS pattern176 in the resource blocks in a region around the DC 162 tone. Forinstance, the DMRS pattern 176 may be adjusted for four PRBs on bothsides of the DC 162 tone, whereas the DMRS pattern 176 of the remainingPRBs may not change, as further described herein with respect to FIG.2D. In some aspects, the DC subcarrier 162 may also be referred to as aDC tone.

Further, in some aspects, adjusting the DMRS pattern 176 may occur whenthe allocation of resources for the UE 110 is less than or equal to ‘X’PRBs and/or when the precoding resource group (PRG) size is less than orequal to ‘Y’ PRG. For example, if a PRG size is set to a defined value,the receiver (e.g., gNB) may assume that the same precoder is appliedover a consecutive number RBs equal to the defined value, and therebymay perform channel estimation over the consecutive number RBs equal tothe defined value. In some aspects, the higher the PRG, the lower theeffect that a collision may have as there may be more resource elementsfor channel estimation. On the other hand, if the resource allocation islarge and the number of PRB is reasonably large (e.g., greater than‘X’), then even if there is a collision, there may not be acorresponding performance loss. Similarly, if the resource allocation islarge, and if the PRG is small, e.g., 2 PRBs, then the base station 105may perform channel estimation using 2 PRBs at a time such that the PRBsthat contain the DC 162 may experience some loss in performance.Moreover, in the event of a collision of DMRS 178 with DC 162, the PRGmay be configured to be large, i.e., greater than ‘Y’ (e.g., both thebase station 105 and the UE 110 may agree that the PRG may be at least4).

The wireless communication network 100 may include one or more basestations 105, one or more UEs 110, and a core network 115. The corenetwork 115 may provide user authentication, access authorization,tracking, internet protocol (IP) connectivity, and other access,routing, or mobility functions. The base stations 105 may interface withthe core network 115 through backhaul links 120 (e.g., S1, etc.). Thebase stations 105 may perform radio configuration and scheduling forcommunication with the UEs 110, or may operate under the control of abase station controller (not shown). In various examples, the basestations 105 may communicate, either directly or indirectly (e.g.,through core network 115), with one another over backhaul links 125(e.g., X1, etc.), which may be wired or wireless communication links.

The base stations 105 may wirelessly communicate with the UEs 110 viaone or more base station antennas. Each of the base stations 105 mayprovide communication coverage for a respective geographic coverage area130. In some examples, base stations 105 may be referred to as a basetransceiver station, a radio base station, an access point, an accessnode, a radio transceiver, a NodeB, eNodeB (eNB), gNodeB (gNB), HomeNodeB, a Home eNodeB, a relay, or some other suitable terminology. Thegeographic coverage area 130 for a base station 105 may be divided intosectors or cells making up only a portion of the coverage area (notshown). The wireless communication network 100 may include base stations105 of different types (e.g., macro base stations or small cell basestations, described below). Additionally, the plurality of base stations105 may operate according to different ones of a plurality ofcommunication technologies (e.g., 5G (New Radio or “NR”), fourthgeneration (4G)/LTE, 3G, Wi-Fi, Bluetooth, etc.), and thus there may beoverlapping geographic coverage areas 130 for different communicationtechnologies.

In some examples, the wireless communication network 100 may be orinclude one or any combination of communication technologies, includinga new radio (NR) or 5G technology, a Long Term Evolution (LTE) orLTE-Advanced (LTE-A) or MuLTEfire technology, a Wi-Fi technology, aBluetooth technology, or any other long or short range wirelesscommunication technology. In LTE/LTE-A/MuLTEfire networks, the termevolved node B (eNB) may be generally used to describe the base stations105, while the term UE may be generally used to describe the UEs 110.The wireless communication network 100 may be a heterogeneous technologynetwork in which different types of eNBs provide coverage for variousgeographical regions. For example, each eNB or base station 105 mayprovide communication coverage for a macro cell, a small cell, or othertypes of cell. The term “cell” is a 3GPP term that can be used todescribe a base station, a carrier or component carrier associated witha base station, or a coverage area (e.g., sector, etc.) of a carrier orbase station, depending on context.

A macro cell may generally cover a relatively large geographic area(e.g., several kilometers in radius) and may allow unrestricted accessby UEs 110 with service subscriptions with the network provider.

A small cell may include a relative lower transmit-powered base station,as compared with a macro cell, that may operate in the same or differentfrequency bands (e.g., licensed, unlicensed, etc.) as macro cells. Smallcells may include pico cells, femto cells, and micro cells according tovarious examples. A pico cell, for example, may cover a small geographicarea and may allow unrestricted access by UEs 110 with servicesubscriptions with the network provider. A femto cell may also cover asmall geographic area (e.g., a home) and may provide restricted accessand/or unrestricted access by UEs 110 having an association with thefemto cell (e.g., in the restricted access case, UEs 110 in a closedsubscriber group (CSG) of the base station 105, which may include UEs110 for users in the home, and the like). A micro cell may cover ageographic area larger than a pico cell and a femto cell, but smallerthan a macro cell. An eNB for a macro cell may be referred to as a macroeNB. An eNB for a small cell may be referred to as a small cell eNB, apico eNB, a femto eNB, or a home eNB. An eNB may support one or multiple(e.g., two, three, four, and the like) cells (e.g., component carriers).

The communication networks that may accommodate some of the variousdisclosed examples may be packet-based networks that operate accordingto a layered protocol stack and data in the user plane may be based onthe IP. A user plane protocol stack (e.g., packet data convergenceprotocol (PDCP), radio link control (RLC), MAC, etc.), may performpacket segmentation and reassembly to communicate over logical channels.For example, a MAC layer may perform priority handling and multiplexingof logical channels into transport channels. The MAC layer may also usehybrid automatic repeat/request (HARQ) to provide retransmission at theMAC layer to improve link efficiency. In the control plane, the RRCprotocol layer may provide establishment, configuration, and maintenanceof an RRC connection between a UE 110 and the base station 105. The RRCprotocol layer may also be used for core network 115 support of resourceblocks for the user plane data. At the physical (PHY) layer, thetransport channels may be mapped to physical channels.

The UEs 110 may be dispersed throughout the wireless communicationnetwork 100, and each UE 110 may be stationary or mobile. A UE 110 mayalso include or be referred to by those skilled in the art as a mobilestation, a subscriber station, a mobile unit, a subscriber unit, awireless unit, a remote unit, a mobile device, a wireless device, awireless communications device, a remote device, a mobile subscriberstation, an access terminal, a mobile terminal, a wireless terminal, aremote terminal, a handset, a user agent, a mobile client, a client, orsome other suitable terminology. A UE 110 may be a cellular phone, asmart phone, a personal digital assistant (PDA), a wireless modem, awireless communication device, a handheld device, a tablet computer, alaptop computer, a cordless phone, a smart watch, a wireless local loop(WLL) station, an entertainment device, a vehicular component, acustomer premises equipment (CPE), or any device capable ofcommunicating in wireless communication network 100. Additionally, a UE110 may be Internet of Things (IoT) and/or machine-to-machine (M2M) typeof device, e.g., a low power, low data rate (relative to a wirelessphone, for example) type of device, that may in some aspects communicateinfrequently with wireless communication network 100 or other UEs. A UE110 may be able to communicate with various types of base stations 105and network equipment including macro eNBs, small cell eNBs, macro gNBs,small cell gNBs, relay base stations, and the like.

A UE 110 may be configured to establish one or more wirelesscommunication links 135 with one or more base stations 105. The wirelesscommunication links 135 shown in wireless communication network 100 maycarry uplink (UL) transmissions from a UE 110 to a base station 105, ordownlink (DL) transmissions, from a base station 105 to a UE 110. Thedownlink transmissions may also be called forward link transmissionswhile the uplink transmissions may also be called reverse linktransmissions. Each wireless communication link 135 may include one ormore carriers, where each carrier may be a signal made up of multiplesub-carriers (e.g., waveform signals of different frequencies) modulatedaccording to the various radio technologies described above. Eachmodulated signal may be sent on a different sub-carrier and may carrycontrol information (e.g., reference signals, control channels, etc.),overhead information, user data, etc. In an aspect, the wirelesscommunication links 135 may transmit bidirectional communications usingfrequency division duplex (FDD) (e.g., using paired spectrum resources)or time division duplex (TDD) operation (e.g., using unpaired spectrumresources). Frame structures may be defined for FDD (e.g., framestructure type 1) and TDD (e.g., frame structure type 2). Moreover, insome aspects, the wireless communication links 135 may represent one ormore broadcast channels.

In some aspects of the wireless communication network 100, base stations105 or UEs 110 may include multiple antennas for employing antennadiversity schemes to improve communication quality and reliabilitybetween base stations 105 and UEs 110. Additionally or alternatively,base stations 105 or UEs 110 may employ multiple input multiple output(MIMO) techniques that may take advantage of multi-path environments totransmit multiple spatial layers carrying the same or different codeddata.

Wireless communication network 100 may support operation on multiplecells or carriers, a feature which may be referred to as carrieraggregation (CA) or multi-carrier operation. A carrier may also bereferred to as a component carrier (CC), a layer, a channel, etc. Theterms “carrier,” “component carrier,” “cell,” and “channel” may be usedinterchangeably herein. A UE 110 may be configured with multipledownlink CCs and one or more uplink CCs for carrier aggregation. Carrieraggregation may be used with both FDD and TDD component carriers. Thebase stations 105 and UEs 110 may use spectrum up to Y MHz (e.g., Y=5,10, 15, or 20 MHz) bandwidth per carrier allocated in a carrieraggregation of up to a total of Yx MHz (x=number of component carriers)used for transmission in each direction. The carriers may or may not beadjacent to each other. Allocation of carriers may be asymmetric withrespect to DL and UL (e.g., more or less carriers may be allocated forDL than for UL). The component carriers may include a primary componentcarrier and one or more secondary component carriers. A primarycomponent carrier may be referred to as a primary cell (PCell) and asecondary component carrier may be referred to as a secondary cell(SCell).

The wireless communications network 100 may further include basestations 105 operating according to Wi-Fi technology, e.g., Wi-Fi accesspoints, in communication with UEs 110 operating according to Wi-Fitechnology, e.g., Wi-Fi stations (STAs) via communication links in anunlicensed frequency spectrum (e.g., 5 GHz). When communicating in anunlicensed frequency spectrum, the STAs and AP may perform a clearchannel assessment (CCA) or listen before talk (LBT) procedure prior tocommunicating in order to determine whether the channel is available.

One or more of base stations 105 and/or UEs 110 may operate according toa NR or 5G technology referred to as millimeter wave (mmW or mmwave)technology. For example, mmW technology includes transmissions in mmWfrequencies and/or near mmW frequencies. Extremely high frequency (EHF)is part of the radio frequency (RF) in the electromagnetic spectrum. EHFhas a range of 30 GHz to 300 GHz and a wavelength between 1 millimeterand 10 millimeters. Radio waves in this band may be referred to as amillimeter wave. Near mmW may extend down to a frequency of 3 GHz with awavelength of 100 millimeters. For example, the super high frequency(SHF) band extends between 3 GHz and 30 GHz, and may also be referred toas centimeter wave. Communications using the mmW and/or near mmW radiofrequency band has extremely high path loss and a short range. As such,base stations 105 and/or UEs 110 operating according to the mmWtechnology may utilize beamforming in their transmissions to compensatefor the extremely high path loss and short range.

Referring to FIGS. 2A-2D, for instance, various transmission schemes areshown according to distinct DMRS patterns. The transmission schemes mayinclude or otherwise be formed of a plurality of resource elements. Assuch, each designated region or portion may be formed of one or moreresource elements. The transmission schemes may be a slot 204 of adefined length of a number of symbols along the time domain (e.g., 14 or28 symbols). Further, the transmission schemes may include one or moreresource blocks including a resource block 202 that includes at least 12subcarriers (e.g., along the frequency domain). The transmission schemesmay include a control region 206 for downlink control data (e.g., 1symbol length), a gap region 208 (e.g., 1 symbol length), a DMRS regionaccording to a DMRS pattern 210 a-g (e.g., 1 symbol length), a dataregion 212 (e.g., 9 symbols), a DC subcarrier 218 (e.g., spanning acrossall symbols), and an uplink common burst 214 (e.g., 2 symbols). In someaspects, the data 212 region may be for uplink transmission on aphysical uplink shared channel (PUSCH). In some aspects, the uplinkcommon burst 214 may be based on a grant, and may include resourcescommon across one or more UEs (sounding reference signal (SRS), pilotsfor uplink, etc.).

The DMRS patterns 210 a-g may include distinct comb patterns by whichthe DMRS 178 may be transmitted. For example, a single comb pattern(e.g., second DMRS pattern 210 b) may allocate all resources of one OFDMsymbol for a single UE such as UE 110 for DMRS transmissions. As such,all resource elements within the resource block allocated for DMRS maybe used by a single UE. However, a two comb pattern (e.g., first DMRSpattern 210 a) may allocate every other resource element of one OFDMsymbol within a resource block to one UE for DMRS, and the remainingresource elements to another UE. For example, in a two comb DMRSpattern, every even resource element may be allocated or assigned to oneUE such as UE 110, and every odd resource element may be allocated orassigned to another UE (or vice versa). In some aspects, a resourceblock such as resource block 202 may refer to or otherwise include aregion across ‘M’ subcarrier and ‘N’ OFDM symbols (e.g., M=12 and N=14).

FIG. 2A shows a conceptual diagram of a first transmission scheme 200having a first DMRS pattern 210 a and a second transmission scheme 220having a second DMRS pattern 210 b. For example, the first comb pattern210 a may correspond to a two comb pattern. Further the firsttransmission scheme 200 and second transmission scheme 220 may each havetwo cyclic shifts. As such, the first DMRS pattern 210 a may be one withtwo combs and two cyclic shifts. The UE 110 may be scheduled (e.g., bybase station 105) to transmit the DMRS 178 in the comb 216 of first DMRSpattern 210 a that contains the DC 162 tone, which may result in acollision 216 and poor channel estimation. Accordingly, the UE 110 mayadjust to the second DMRS pattern 210 b of the second transmissionscheme 220 to transmit using the single comb pattern.

The second DMRS pattern 210 b may be applied to or may be adjustedacross the entire scheduled bandwidth. That is, in some aspects, thesecond DMRS pattern 210 b may be adjusted for an entire allocation(e.g., for all resource blocks), and not just for the resource elementssurrounding the DC 162. Further, although collision 216 is not avoidedin the second transmission scheme 220, the channel estimation loss inlosing one pilot may be smaller in the second DMRS pattern 210 bcompared to the first DMRS pattern 210 a of the first transmissionscheme 200 because the percentage of pilots lost is smaller (e.g.,losing 1 out of 12 resource elements according to the DMRS pattern 210compared to 1 out of 24 resource elements in the second DMRS pattern 210b). Also, in the first DMRS pattern 210 a there may be a gap of threeresource elements when collision 216 occurs, thereby resulting in aninterpolation across multiple gaps compared to one gap for the secondDMRS pattern 210 b.

The receiver, or base station 105, may be aware of the DMRS adjustmentor expected DMRS adjustment (e.g., from the first DMRS pattern 210 a tothe second DMRS pattern 210 b) based on the scheduling of the DMRS 178transmission at the DC 162 tone by the base station 105. In someaspects, the base station 105 and the UE 110 may coordinate or may havecoordinated the adjusted DMRS pattern (e.g., second DMRS pattern 210 b)to use in the event of a collision 216. However, in some aspects, thebase station 105 may, via semi-static signaling, transmit an indicationto the UE 110 indicating the adjusted DMRS pattern to use when collision216 occurs.

FIG. 2B shows a conceptual diagram of an adjustment of a DMRS patternfrom the second DMRS pattern 210 b to a third DMRS pattern 210 c. Thesecond transmission scheme 220 includes an scheduled transmission ofDMRS 178 according to the second DMRS pattern 210 b colliding with theDC subcarrier 218. For example, the second DMRS pattern 210 b maycorrespond to a single comb DMRS pattern. The UE 110 may initially beconfigured to transmit according to the second DMRS pattern 210 b.However, when an increase in transmit power (e.g., double the power) isavailable and/or channel conditions at the receiver are adequate asindicated by the base station 105, the UE 110 may adjust from the secondDMRS pattern 210 b to a third DMRS pattern 210 c as shown in a thirdtransmission scheme 240. The third DMRS pattern 210 c ensures that noassociated resource element overlaps with the DC 162 tone. That is, noneof the DMRS 178 transmissions of the third DMRS pattern 210 c collidewith the DC subcarrier 162. For example, a two comb DMRS pattern, or anycomb-based pattern greater than one, may configure a location of DMRS178 and the DC subcarrier 162 in non-overlapping resource elements.

As such, even though the number of resource elements is reduced (e.g.,from 12 resource elements in the second DMRS pattern 210 b to 6 in thethird DMRS pattern 210 c), the gain from an increase in transmit poweroutweighs the decrease in the number of resources used for DMRStransmission (e.g., half the resources). That is, if channel conditionsat the receiver (e.g., gNB) are sufficient, the increase in transmitpower, if possible by the UE 110, or power boost, may compensate for thereduction in resources allocated for DMRS. The third DMRS pattern 210 cmay include two cyclic shifts. Such adjustment to the third DMRS pattern210 c from the second DMRS pattern 210 b may provide gains in noiselimited scenarios but not in interference limited scenarios, or ingeneral such an adjustment would provide gains when the power boostingmay compensate for the reduction of the resources for DMRS.

FIG. 2C shows a conceptual diagram of a fourth transmission scheme 250including an adjusted DMRS pattern 210 d in a region surrounding theresource element where the collision 216 is scheduled to occur. Forexample, within resource block 202 b, a collision 216 between the DMRS178 and a DC subcarrier 178 at a particular resource element may bescheduled to occur. Accordingly, the UE 110 may use an adjusted DMRSpattern 210 d rather than the initial DMRS pattern 210 e within theresource block 202 b where the collision may occur. The adjusted DMRSpattern 210 d may correspond to a single comb DMRS pattern where anincrease in the number of resource elements for DMRS may mitigate theeffect of losing one resource element to the collision with the DC tone162. However, within resource blocks 202 a and 202 c, no such collisionexists or may be expected to take place, and as such, the initial DMRSpattern 210 e may not be adjusted.

However, the adjusted DMRS pattern 210 d may be provided in a region ofthe resource blocks around the DC tone 162. In one example, the DMRSpattern may be adjusted for ‘X’ number of resource blocks around the DCtone 162, whereas the DMRS pattern 210 e of remaining resource blocks202 a and 202 c may not change. The fourth transmission scheme 250 mayinclude an adjusted DMRS pattern 210 d for the resource blocks thatcontain the DC tone 162 and/or where collision occurs. In such instance,a two comb DMRS pattern corresponding to the initial DMRS pattern 210 emay be adjusted to a single comb DMRS pattern 210 d. In some aspects,equal number of resource blocks may change to an adjusted DMRS patternfrom either side of the resource allocation. In such a scenario, thereceiver, or base station 105, may get an enhanced channel estimationaround the affected region, and decrease the impact of the DC subcarrier162 collision with the DMRS 178.

FIG. 2D shows a conceptual diagram of a fifth transmission scheme 260including at least two symbols allocated for DMRS transmission. Forexample, the UE 110 may, upon detecting a collision 216 between the DMRS178 and the DC tone 162 on a particular resource element, schedule orallocate an additional symbol for another DMRS transmissionnon-overlapping or not colliding with the DC subcarrier 218 within thesame slot and/or resource block 202. When collision occurs, theadditional DMRS 210 g may be staggered in the sense that the collisionis avoided in the second OFDM symbol. That is, when collision happens,the UE 110 may also transmit an additional DMRS 210 g with such apattern. Both the base station 105 and the UE 110 may be aware of theadjustment without signaling between the two entities.

Referring to FIG. 3, for example, a method 300 of wireless communicationin operating a UE, such as UE 110, according to the above-describedaspects to adjust a DMRS pattern may include one or more of theherein-defined actions. The blocks illustrated as having dashed linesmay be optional.

At block 304, method 300 may determine an upcoming occurrence of acollision between a DMRS and a DC subcarrier, the occurrence of thecollision being that both the DMRS and the DC subcarrier occupy at leasta same resource element within a resource block in a scheduled uplinktransmission. For example, as described herein, the UE 110 may executethe modem 140 and/or collision mitigation component 170 to determine anupcoming occurrence of a collision 216 between a DMRS 178 and a DCsubcarrier 162, the occurrence of the collision being that both the DMRS178 and the DC subcarrier 162 occupy at least a same resource elementwithin a resource block 202 in a scheduled uplink transmission.

At block 304, the method 300 may determine whether a resource allocationcorresponding to at least one of a number of resource blocks or aprecoding resource group satisfies a resource allocation threshold. Forexample, as described herein, the UE 110 may execute the modem 140and/or collision mitigation component 170 to determine whether aresource allocation corresponding to at least one of a number ofresource blocks or a precoding resource group satisfies a resourceallocation threshold. In some aspects, the resource allocation thresholdmay represent a minimum number of allocated resources for triggeringadjustment of the DMRS pattern.

At block 306, the method 300 may adjust a DMRS pattern within at leastthe resource block. For example, as described herein, the UE 110 mayexecute the modem 140 and/or DMRs pattern determination component 172 toadjust a DMRS pattern 176 within at least the resource block 202 basedon determining the upcoming occurrence of the collision between the DMRS176 and the DC subcarrier 162 both occupying the at least a sameresource element of the resource element 202 in the scheduled uplinktransmission.

In some aspects, adjusting the DMRS pattern 176 may include adjusting anumber of combs of the DMRS pattern 176. In some aspects, adjusting thenumber of combs of the DMRS pattern 176 may include adjusting from acomb DMRS pattern greater than one (e.g., two comb DMRS pattern) to asingle comb DMRS pattern. In some aspects, adjusting from the comb DMRSpattern greater than one to the single comb DMRS pattern corresponds toan increase in a number of resource elements available for DMRStransmissions and correspondingly channel estimation. In some aspects,the DMRS 178 and the DC subcarrier 162 may maintain overlap (e.g., stillcollide) within at least one resource element of the single comb DMRSpattern following adjustment of the DMRS pattern 176.

In some aspects, adjusting the number of combs of the DMRS pattern 176may include adjusting from a single comb DMRS pattern 176 to a comb DMRSpattern greater than one based on determining that the transmit powerincrease is available for the scheduled uplink transmission, andforegoing adjustment of the DMRS pattern 176 based on determining thatthe transmit power increase is not available for the scheduled uplinktransmission.

In some aspects, adjusting the DMRS pattern 176 within the at least theresource block may include adjusting the DMRS pattern 176 based ondetermining that the resource allocation corresponding to at least oneof the number of resource blocks or the precoding resource groupsatisfies the resource allocation threshold, and foregoing adjustment ofthe DMRS pattern 176 based on determining that the resource allocationcorresponding to at least one of the number of resource blocks or theprecoding resource group does not satisfy the resource allocationthreshold.

In some aspects, the scheduled uplink transmission may include theresource block and at least one additional resource block, and adjustingthe number of combs of the DMRS pattern 176 may include adjusting thenumber of combs for at least a portion of the resource block, andforegoing adjustment of the number of combs for the at least oneadditional resource block.

In some aspects, adjusting the DMRS pattern 176 may include allocatingone or more additional resource elements in at least one OFDM symbolwithin a slot of the scheduled uplink transmission for a subsequent DMRSthat is non-overlapping with the DC subcarrier.

In some aspects, the DMRS pattern 176 may be associated with a firstconfiguration type. For example, the first configuration type may be oneof comb-based with comb-2 or non-comb-based. In some aspects, adjustingthe DMRS pattern 176 may include selecting a second configuration typedifferent from the first configuration type. For example, the secondconfiguration type may be a different one of comb-based with comb-2 ornon-comb-based.

In some aspects, although not shown, the method 300 may determinewhether a transmit power increase is available for the scheduled uplinktransmission. In some aspects, the comb DMRS pattern 176 greater thanone may be configured for the DMRS 178 and the DC subcarrier 162 to bein non-overlapping resource elements of the resource block. In someaspects, determining whether the transmit power increase is availablemay include receiving an indication from a network entity (e.g., basestation 105) notifying the UE 110 of at least one of an unavailabilityof the transmit power increase or channel conditions at the networkentity, the channel conditions corresponding to at least one ofinterference or noise limitations at the network entity. In someaspects, adjusting the number of combs of the DMRS pattern 176 mayinclude foregoing adjustment of the DMRS pattern 176 based on receivingthe indication from the network entity.

At block 308, the method 300 may transmit at least the DMRS during thescheduled uplink transmission according to the adjusted DMRS pattern.For instance, as described herein, the UE 110 may execute transceiver502 and/or RF front end 588 to transmit at least the DMRS 178 during thescheduled uplink transmission according to the adjusted DMRS pattern.

At block 310, the method 300 may transmit at least the DMRS during thescheduled uplink transmission according to an unadjusted DMRS pattern.For instance, as described herein, the UE 110 may execute transceiver502 and/or RF front end 588 to transmit at least the DMRS 178 during thescheduled uplink transmission according to an unadjusted DMRS pattern.

In some aspects, although not shown, the method 300 may receive anindication from a network entity (e.g., base station 105) identifyingthe adjusted DMRS pattern. In some aspects, the DMRS pattern 176 may beadjusted for an entire resource allocation including the resource block202.

Referring to FIG. 4, for example, a method 400 of wireless communicationat a network entity (e.g., base station 105) according to theabove-described aspects to determine a DMRS-DC collision and transmit anindication to at least one UE 110 indicating at least one of an adjustedDMRS pattern or an uplink transmission limiting scenario includes one ormore of the herein-defined actions. The blocks illustrated as havingdashed lines may be optional.

At block 402, the method 400 may determine an upcoming occurrence of acollision between a DMRS and a DC subcarrier, the occurrence of thecollision being that both the DMRS and the DC subcarrier occupy at leasta same resource element within a resource block in a scheduled uplinktransmission from a UE. For example, as described herein, the basestation 105 and/or modem 160 may execute collision detection component150 to determine an upcoming occurrence of a collision 216 between aDMRS 178 and a DC subcarrier 162, the occurrence of the collision beingthat both the DMRS 178 and the DC subcarrier 162 occupy at least a sameresource element within a resource block in a scheduled uplinktransmission from a UE 110.

At block 404, the method 400 may determine an uplink transmissionlimiting scenario at the network entity based on one or more channelconditions. For example, as described herein, the base station 105and/or modem 160 may execute uplink limitation determination component172 to determine an uplink transmission limiting scenario at the networkentity based on one or more channel conditions. In some aspects, the oneor more channel conditions may correspond to at least one ofinterference or noise limitations at the network entity (e.g., basestation 105).

At block 406, the method 400 may transmit an indication to the UEdenoting the uplink transmission limiting scenario. For example, asdescribed herein, the base station 105 and/or modem 160 may executetransceiver 602 and/or RF front end 688 to transmit an indication to theUE 110 denoting the uplink transmission limiting scenario.

At block 408, the method 400 may determine that the UE should transmitthe DMRS according to an adjusted DMRS pattern based on the one or morechannel conditions at the network entity. For example, as describedherein, the base station 105 and/or modem 160 may execute uplinklimitation determination component 172 to determine that the UE 110should transmit the DMRS 178 according to an adjusted DMRS pattern 176based on the one or more channel conditions at the network entity 105.

At block 410, the method 400 may transmit the adjusted DMRS pattern tothe UE on a downlink communication channel. For example, as describedherein, the base station 105 and/or modem 160 may execute transceiver602 and/or RF front end 688 to transmit the adjusted DMRS pattern 176 tothe UE 110 on a downlink communication channel. In some aspects, theadjusted DMRS pattern may include at least one of a single comb DMRSpattern, a comb DMRS pattern greater than one, a varying comb DMRSpattern across an entire resource allocation, or a staggered comb DMRSpattern corresponding to at least two DMRS transmissions within theresource block.

In some aspects, although not shown, the method 400 may receive theuplink transmission including the DMRS 178 according to the adjustedDMRS pattern.

Referring to FIG. 5, one example of an implementation of UE 110 mayinclude a variety of components, some of which have already beendescribed above, but including components such as one or more processors512 and memory 516 and transceiver 502 in communication via one or morebuses 544, which may operate in conjunction with modem 140 and collisionmitigation component 170 to enable one or more of the functionsdescribed herein. Further, the one or more processors 512, modem 514,memory 516, transceiver 502, radio frequency (RF) front end 588 and oneor more antennas 565, may be configured to support voice and/or datacalls (simultaneously or non-simultaneously) in one or more radio accesstechnologies. In some aspects, the modem 514 may be the same as orsimilar to the modem 514.

In an aspect, the one or more processors 512 can include a modem 514that uses one or more modem processors. The various functions related toresource identification component 150 may be included in modem 140and/or processors 512 and, in an aspect, can be executed by a singleprocessor, while in other aspects, different ones of the functions maybe executed by a combination of two or more different processors. Forexample, in an aspect, the one or more processors 512 may include anyone or any combination of a modem processor, or a baseband processor, ora digital signal processor, or a transmit processor, or a receiverprocessor, or a transceiver processor associated with transceiver 502.In other aspects, some of the features of the one or more processors 512and/or modem 140 associated with resource identification component 150may be performed by transceiver 502.

The memory 516 may be configured to store data used herein and/or localversions of applications 575 or retransmission component 170 and/or oneor more of the subcomponents being executed by at least one processor512. Memory 516 can include any type of computer-readable medium usableby a computer or at least one processor 512, such as random accessmemory (RAM), read only memory (ROM), tapes, magnetic discs, opticaldiscs, volatile memory, non-volatile memory, and any combinationthereof. In an aspect, for example, memory 516 may be a non-transitorycomputer-readable storage medium that stores one or morecomputer-executable codes defining resource identification component 150and/or one or more of its subcomponents, and/or data associatedtherewith, when UE 110 is operating at least one processor 512 toexecute retransmission component 170 and/or one or more of itssubcomponents.

Transceiver 502 may include at least one receiver 506 and at least onetransmitter 508. Receiver 506 may include hardware, firmware, and/orsoftware code executable by a processor for receiving data, the codecomprising instructions and being stored in a memory (e.g.,computer-readable medium). Receiver 506 may be, for example, a RFreceiver. In an aspect, receiver 506 may receive signals transmitted byat least one base station 125. Additionally, receiver 506 may processsuch received signals, and also may obtain measurements of the signals,such as, but not limited to, Ec/Io, SNR, RSRP, RSSI, etc. Transmitter508 may include hardware, firmware, and/or software code executable by aprocessor for transmitting data, the code comprising instructions andbeing stored in a memory (e.g., computer-readable medium). A suitableexample of transmitter 508 may include , but is not limited to, an RFtransmitter.

Moreover, in an aspect, UE 110 may include RF front end 588, which mayoperate in communication with one or more antennas 565 and transceiver502 for receiving and transmitting radio transmissions, for example,wireless communications transmitted by at least one base station 125 orwireless transmissions transmitted by UE 110. RF front end 588 may becommunicatively coupled with one or more antennas 565 and can includeone or more low-noise amplifiers (LNAs) 590, one or more switches 592,one or more power amplifiers (PAs) 598, and one or more filters 596 fortransmitting and receiving RF signals.

In an aspect, LNA 590 can amplify a received signal at a desired outputlevel. In an aspect, each LNA 590 may have a specified minimum andmaximum gain values. In an aspect, RF front end 588 may use one or moreswitches 592 to select a particular LNA 590 and its specified gain valuebased on a desired gain value for a particular application.

Further, for example, one or more PA(s) 598 may be used by RF front end588 to amplify a signal for an RF output at a desired output powerlevel. In an aspect, each PA 598 may have specified minimum and maximumgain values. In an aspect, RF front end 588 may use one or more switches592 to select a particular PA 598 and a corresponding specified gainvalue based on a desired gain value for a particular application.

Also, for example, one or more filters 596 can be used by RF front end588 to filter a received signal to obtain an input RF signal. Similarly,in an aspect, for example, a respective filter 596 can be used to filteran output from a respective PA 598 to produce an output signal fortransmission. In an aspect, each filter 596 can be communicativelycoupled with a specific LNA 590 and/or PA 598. In an aspect, RF frontend 588 can use one or more switches 592 to select a transmit or receivepath using a specified filter 596, LNA 590, and/or PA 598, based on aconfiguration as specified by transceiver 502 and/or processor 512.

As such, transceiver 502 may be configured to transmit and receivewireless signals through one or more antennas 565 via RF front end 588.In an aspect, transceiver may be tuned to operate at specifiedfrequencies such that UE 110 can communicate with, for example, one ormore base stations 125 or one or more cells associated with one or morebase stations 125. In an aspect, for example, modem 140 can configuretransceiver 502 to operate at a specified frequency and power levelbased on the UE configuration of the UE 110 and the communicationprotocol used by modem 140.

In an aspect, modem 140 can be a multiband-multimode modem, which canprocess digital data and communicate with transceiver 502 such that thedigital data is sent and received using transceiver 502. In an aspect,modem 140 can be multiband and be configured to support multiplefrequency bands for a specific communications protocol. In an aspect,modem 140 can be multimode and be configured to support multipleoperating networks and communications protocols. In an aspect, modem 140can control one or more components of UE 110 (e.g., RF front end 588,transceiver 502) to enable transmission and/or reception of signals fromthe network based on a specified modem configuration. In an aspect, themodem configuration can be based on the mode of the modem and thefrequency band in use. In another aspect, the modem configuration can bebased on UE configuration information associated with UE 110 as providedby the network during cell selection and/or cell reselection.

Referring to FIG. 6, one example of an implementation of base station105 may include a variety of components, some of which have already beendescribed above, but including components such as one or more processors612, a memory 616, and a transceiver 602 in communication via one ormore buses 644, which may operate in conjunction with modem 160 andcollision detection component 150 to enable one or more of the functionsdescribed herein.

The transceiver 602, receiver 606, transmitter 608, one or moreprocessors 612, memory 616, applications 675, buses 644, RF front end688, LNAs 690, switches 692, filters 696, PAs 698, and one or moreantennas 665 may be the same as or similar to the correspondingcomponents of UE 110, as described above, but configured or otherwiseprogrammed for base station operations as opposed to UE operations.

The above detailed description set forth above in connection with theappended drawings describes examples and does not represent the onlyexamples that may be implemented or that are within the scope of theclaims. The term “example,” when used in this description, means“serving as an example, instance, or illustration,” and not “preferred”or “advantageous over other examples.” The detailed description includesspecific details for the purpose of providing an understanding of thedescribed techniques. These techniques, however, may be practicedwithout these specific details. In some instances, well-known structuresand apparatuses are shown in block diagram form in order to avoidobscuring the concepts of the described examples.

Information and signals may be represented using any of a variety ofdifferent technologies and techniques. For example, data, instructions,commands, information, signals, bits, symbols, and chips that may bereferenced throughout the above description may be represented byvoltages, currents, electromagnetic waves, magnetic fields or particles,optical fields or particles, computer-executable code or instructionsstored on a computer-readable medium, or any combination thereof.

The various illustrative blocks and components described in connectionwith the disclosure herein may be implemented or performed with aspecially-programmed device, such as but not limited to a processor, adigital signal processor (DSP), an ASIC, a FPGA or other programmablelogic device, a discrete gate or transistor logic, a discrete hardwarecomponent, or any combination thereof designed to perform the functionsdescribed herein. A specially-programmed processor may be amicroprocessor, but in the alternative, the processor may be anyconventional processor, controller, microcontroller, or state machine. Aspecially-programmed processor may also be implemented as a combinationof computing devices, e.g., a combination of a DSP and a microprocessor,multiple microprocessors, one or more microprocessors in conjunctionwith a DSP core, or any other such configuration.

The functions described herein may be implemented in hardware, softwareexecuted by a processor, firmware, or any combination thereof. Ifimplemented in software executed by a processor, the functions may bestored on or transmitted over as one or more instructions or code on anon-transitory computer-readable medium. Other examples andimplementations are within the scope and spirit of the disclosure andappended claims. For example, due to the nature of software, functionsdescribed above can be implemented using software executed by aspecially programmed processor, hardware, firmware, hardwiring, orcombinations of any of these. Features implementing functions may alsobe physically located at various positions, including being distributedsuch that portions of functions are implemented at different physicallocations. Also, as used herein, including in the claims, “or” as usedin a list of items prefaced by “at least one of” indicates a disjunctivelist such that, for example, a list of “at least one of A, B, or C”means A or B or C or AB or AC or BC or ABC (i.e., A and B and C).

Computer-readable media includes both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. A storage medium may be anyavailable medium that can be accessed by a general purpose or specialpurpose computer. By way of example, and not limitation,computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or otheroptical disk storage, magnetic disk storage or other magnetic storagedevices, or any other medium that can be used to carry or store desiredprogram code means in the form of instructions or data structures andthat can be accessed by a general-purpose or special-purpose computer,or a general-purpose or special-purpose processor. Also, any connectionis properly termed a computer-readable medium. For example, if thesoftware is transmitted from a website, server, or other remote sourceusing a coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technologies such as infrared, radio,and microwave, then the coaxial cable, fiber optic cable, twisted pair,DSL, or wireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,include compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and Blu-ray disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Combinations of the above are also included within the scope ofcomputer-readable media.

The previous description of the disclosure is provided to enable aperson skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the common principles defined herein may beapplied to other variations without departing from the spirit or scopeof the disclosure. Furthermore, although elements of the describedaspects and/or embodiments may be described or claimed in the singular,the plural is contemplated unless limitation to the singular isexplicitly stated. Additionally, all or a portion of any aspect and/orembodiment may be utilized with all or a portion of any other aspectand/or embodiment, unless stated otherwise. Thus, the disclosure is notto be limited to the examples and designs described herein but is to beaccorded the widest scope consistent with the principles and novelfeatures disclosed herein.

What is claimed is:
 1. A method of wireless communications at a userequipment (UE), comprising: determining an upcoming occurrence of acollision between a demodulation reference signal (DMRS) and a directcurrent (DC) subcarrier, the occurrence of the collision being that boththe DMRS and the DC subcarrier occupy at least a same resource elementof a resource block in a scheduled uplink transmission; and adjusting aDMRS pattern within at least the resource block based on determining theupcoming occurrence of the collision.
 2. The method of claim 1, whereinadjusting the DMRS pattern includes adjusting a number of combs of theDMRS pattern.
 3. The method of claim 2, wherein adjusting the number ofcombs of the DMRS pattern includes adjusting from a comb DMRS patterngreater than one to a single comb DMRS pattern.
 4. The method of claim3, wherein adjusting from the comb DMRS pattern greater than one to thesingle comb DMRS pattern corresponds to an increase in a number ofresource elements available for channel estimation.
 5. The method ofclaim 3, wherein the DMRS and the DC subcarrier maintain overlap withinat least one resource element of the single comb DMRS pattern followingadjustment of the DMRS pattern.
 6. The method of claim 2, furthercomprising determining whether a transmit power increase is availablefor the scheduled uplink transmission, wherein adjusting the number ofcombs of the DMRS pattern includes: adjusting from a single comb DMRSpattern to a comb DMRS pattern greater than one based on determiningthat the transmit power increase is available for the scheduled uplinktransmission; and foregoing adjustment of the DMRS pattern based ondetermining that the transmit power increase is not available for thescheduled uplink transmission.
 7. The method of claim 6, wherein thecomb DMRS pattern greater than one is configured for the DMRS and the DCsubcarrier to be in non-overlapping resource elements of the resourceblock.
 8. The method of claim 6, wherein determining whether thetransmit power increase is available includes receiving an indicationfrom a network entity notifying the UE of at least one of anunavailability of the transmit power increase or channel conditions atthe network entity, the channel conditions corresponding to at least oneof interference or noise limitations at the network entity, and whereinadjusting the number of combs of the DMRS pattern includes foregoingadjustment of the DMRS pattern based on receiving the indication fromthe network entity.
 9. The method of claim 2, wherein the scheduleduplink transmission includes the resource block and at least oneadditional resource block, wherein adjusting the number of combs of theDMRS pattern includes: adjusting the number of combs for at least aportion of the resource block; and foregoing adjustment of the number ofcombs for the at least one additional resource block.
 10. The method ofclaim 1, wherein the DMRS pattern is associated with a firstconfiguration type, and wherein adjusting the DMRS pattern includesselecting a second configuration type different from the firstconfiguration type.
 11. The method of claim 1, further comprisingdetermining whether a resource allocation corresponding to at least oneof a number of resource blocks or a precoding resource group satisfies aresource allocation threshold, wherein adjusting the DMRS pattern withinat least the resource block includes: adjusting the DMRS pattern basedon determining that the resource allocation corresponding to at leastone of the number of resource blocks or the precoding resource groupsatisfies the resource allocation threshold; and foregoing adjustment ofthe DMRS pattern based on determining that the resource allocationcorresponding to at least one of the number of resource blocks or theprecoding resource group does not satisfy the resource allocationthreshold.
 12. The method of claim 11, wherein the resource allocationthreshold represents a minimum number of allocated resources fortriggering adjustment of the DMRS pattern.
 13. The method of claim 1,wherein adjusting the DMRS pattern includes allocating one or moreadditional resource elements in at least one OFDM symbol within a slotof the scheduled uplink transmission for a subsequent DMRS that isnon-overlapping with the DC subcarrier.
 14. The method of claim 1,further comprising receiving an indication from a network entityidentifying the adjusted DMRS pattern.
 15. The method of claim 1,wherein the DMRS pattern is adjusted for an entire resource allocationincluding the resource block.
 16. A method wireless communications at anetwork entity, comprising: determining an upcoming occurrence of acollision between a demodulation reference signal (DMRS) and a directcurrent (DC) subcarrier, the occurrence of the collision being that boththe DMRS and the DC subcarrier occupy at least a same resource elementwithin a resource block in a scheduled uplink transmission from a userequipment (UE); determining that the UE should transmit the DMRSaccording to an adjusted DMRS pattern; and transmitting the adjustedDMRS pattern to the UE on a downlink communication channel.
 17. Themethod of claim 16, further comprising: determining an uplinktransmission limiting scenario at the network entity based on one ormore channel conditions; and transmitting an indication to the UEdenoting the uplink transmission limiting scenario.
 18. The method ofclaim 16, wherein the one or more channel conditions corresponding to atleast one of interference or noise limitations at the network entity.19. The method of claim 16, wherein determining that the UE shouldtransmit the DMRS according to the adjusted DMRS is based on the one ormore channel conditions at the network entity.
 20. The method of claim19, further comprising receiving the uplink transmission including theDMRS according to the adjusted DMRS pattern.
 21. The method of claim 19,wherein the adjusted DMRS pattern includes at least one of: a singlecomb DMRS pattern, a comb DMRS pattern greater than one, a varying combDMRS pattern across an entire resource allocation, or a staggered combDMRS pattern corresponding to at least two DMRS transmissions within theresource block.
 22. An apparatus for wireless communications,comprising: a memory; and a processor coupled to the memory andconfigured to: determine an upcoming occurrence of a collision between ademodulation reference signal (DMRS) and a direct current (DC)subcarrier, the occurrence of the collision being that both the DMRS andthe DC subcarrier occupy at least a same resource element within aresource block in a scheduled uplink transmission; and adjust a DMRSpattern within at least the resource block based on determining theupcoming occurrence of the collision.
 23. The apparatus of claim 22,wherein to adjust the DMRS pattern, the processor is further configuredto adjust a number of combs of the DMRS pattern.
 24. The apparatus ofclaim 23, wherein to adjust the number of combs of the DMRS pattern, theprocessor is further configured to adjust from a comb DMRS patterngreater than one to a single comb DMRS pattern.
 25. The apparatus ofclaim 23, wherein the processor is further configured to determinewhether a transmit power increase is available for the scheduled uplinktransmission, wherein to adjust the number of combs of the DMRS pattern,the processor is further configured to: adjust from a single comb DMRSpattern to a comb DMRS pattern greater than one based on determiningthat the transmit power increase is available for the scheduled uplinktransmission; and forego adjustment of the DMRS pattern based ondetermining that the transmit power increase is not available for thescheduled uplink transmission.
 26. The apparatus of claim 23, whereinthe scheduled uplink transmission includes the resource block and atleast one additional resource block, wherein to adjust the number ofcombs of the DMRS pattern, the processor is further configured to:adjust the number of combs for at least a portion of the resource block;and forego adjustment of the number of combs for the at least oneadditional resource block.
 27. The apparatus of claim 22, wherein theprocessor is further configured to determine whether a resourceallocation corresponding to at least one of a number of resource blocksor a precoding resource group satisfies a resource allocation threshold,wherein to adjust the DMRS pattern within at least the resource block,the processor is further configured to: adjust the DMRS pattern based ondetermining that the resource allocation corresponding to at least oneof the number of resource blocks or the precoding resource groupsatisfies the resource allocation threshold; and forego adjustment ofthe DMRS pattern based on determining that the resource allocationcorresponding to at least one of the number of resource blocks or theprecoding resource group does not satisfy the resource allocationthreshold.
 28. The apparatus of claim 22, wherein to adjust the DMRSpattern, the processor is further configured to allocate one or moreadditional resource elements in at least one OFDM symbol within a slotof the scheduled uplink transmission for a subsequent DMRS that isnon-overlapping with the DC subcarrier.
 29. The apparatus of claim 22,wherein the DMRS pattern is associated with a first configuration type,and wherein to adjust the DMRS pattern, the processor is furtherconfigured to select a second configuration type different from thefirst configuration type.
 30. An apparatus for wireless communications,comprising: a memory; and a processor coupled to the memory andconfigured to: determine an upcoming occurrence of a collision between ademodulation reference signal (DMRS) and a direct current (DC)subcarrier, the occurrence of the collision being that both the DMRS andthe DC subcarrier occupy at least a same resource element within aresource block in a scheduled uplink transmission from a user equipment(UE); determine that the UE should transmit the DMRS according to anadjusted DMRS pattern; and transmit the adjusted DMRS pattern to the UEon a downlink communication channel.